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26 Fascinating Phobos Facts for You

Phobos – one of the two moons of Mars, is pretty interesting. It is actually a doomed satellite, which is slowly but surely moving towards is end with every tick of the clock. Most of the names of the Phobos’ features are given after names of the fictitious places of the novel Gulliver’s Travels. There are many such fascinating Phobos facts. Let us learn about a few of those facts…

Before we jump into our topic, let us learn some quick and short facts about Phobos:

Name

Phobos

Satellite of

Mars

Alternative name

Mars I,

Discoverer’s name

Asaph Hall

Discovery date

17th August, 1877

Physical characteristics

Closest approach (Periapsis)

9234.42 km

Farthest approach (Apoapsis)

9517.58 km

Dimensions

27 x 22 x 18 km

Mean radius

11.2667 km

(1.76941 mEarths)

Surface area

1548.3 km2

Volume

5783.61 km3

Mass

1.0659×1016 kg

Mean Density

1.876 g/cm3

Escape Velocity

11.39 m/s OR, 41 km/h OR, 25 mph

Time taken for completion of one orbit

7.65 hours

Orbital speed (average)

2.138 km/s

Mean radius of Phobos

11.2667 km

Fascinating Phobos Facts: 1-13

1. Johannes Kelper propounded that Mars may have two moons. How did he do that? He simply made a random guess and thought that since Mars is between Earth, which has one satellite and Jupiter, which has 4 (back then, Jupiter was known to have 4 satellites). So, Mars may have 2 satellites or moons.

2. No study was conducted to prove it. Everyone thought that Mars had no moons. But it was Asaph Hall, an American astronomer who discovered Phobos and Deimos (two moons of Mars) from Washington D.C.’s U.S. Naval Observatory. He hunted for the moons closer to Martian surface as opposed to previous attempts for looking for a moon away from the planet.

3. Asaph Hall was frustrated at first with all his efforts going in vain but he continued trying with his wife’s persuasion (her name was Angelina). On August 12th, 1877, he found Deimos and on 17th August, 1877, he found Phobos.

4. These moons are so close to the surface of Mars that they mostly go unnoticed, because of the glare of Mars.

5. They are roughly of the size of an asteroid and are considered to be two of the smallest of moons in our solar system.

6. Did you know that Phobos is just 3,700 miles away from Mars? Our moon is roughly 384,000 miles apart from our Earth.

7. Phobos is just 7.24 times heavier that Deimos and it is closer to Mars and it is 4 times faster than Deimos.

8. The names are a bit weird. Phobos is named after one of the sons of Rome’s War God – Ares (Mars). Deimos was also named after one of the sons of the War God. Phobos means fear – remember the word phobia? And Deimos means fleeing especially from the battlefield after getting defeated. Ironically enough these two sons accompanied their father for battles (as per Roman Mythology).

9. Though Hall discovered two moons, no further study was conducted to know about them. It nearly took 100 years to start researching about them.

10. Phobos and Deimos are mystery to scientists. They have some qualities of asteroids and they completely show different properties which are not seen in asteroids. Their origin is also a mystery.

11. There are many hypotheses when it comes to the origin of the moons.

One such hypothesis is that they were asteroids and were present in asteroid belt present between Mars and Jupiter. The asteroids were pulled by Mars gravitational force and were trapped in the orbits in which they are now. Some aspects which Phobos and Deimos shares with asteroids are irregularity in shape, the material with which they are mostly made of – Type I and II carbonaceous chondrites, the same material that asteroids and dwarf planets are made of! However, there are other aspects which don’t go hand in hand with this hypothesis. Phobos’ orbit is perfectly circular in shape and if it were to be believed as an asteroid then having such a perfect circular orbit is not possible. The two satellites of Mars are less dense in comparison with asteroids which proves that these celestial bodies are not asteroids.

The other hypothesis put forward is that Phobos (and Deimos as well) is a part of Mars. When some asteroids collided with Mars, pieces of the planet clubbed together because of gravity and created Phobos. This hypothesis also fails because density wise, Phobos is less dense compare to Mars.

The third hypothesis is that a large protoplanet collided with Mars and created a big satellite which got broken down into tiny satellites. These mother and baby satellites were revolving and in this process, all but two got mixed in the Martian rocky surface.

12. Few studies conducted in 2016 approve this theory and NASA, in 2015, has seen some crevices on the Phobos surface, where the crevices indicate that Phobos is disintegrating and NASA assumes that this is the beginning of the process (see #15).

13. We told that Phobos’ revolves fast, right? If you are wondering how fast it revolves, then here is the answer. It revolves three times in a day (Earth day). In terms of Martian day, it revolves twice. It is seen as rising from west and setting in east. It takes only 4 hours 15 minutes for one revolution.

26 Fascinating Phobos Facts for You was last modified: August 7th, 2017 by Virupakshi Trinayani

Why on earth do you need my biography? I won't say it! Okay, a tiny bit won't hurt. I am technologically and geographically challenged but I love to read about random facts and hence... well, you are not that dumb, are you?